


Wake yourself up; sleep yourself down

by Rainbow_Sprinkles



Category: Undertale (Video Game)
Genre: Backstory, Brief appearances by Toriel and Alphys, Canon-Compliant, Disordered thinking and behavior, Gen, Glimpses from different timelines, Not the healthiest parent-child relationship, Pre-Canon, Present and past tense, Science that conveniently advances the plot, Very gentle knocks on the fourth wall, and has some unethical elements
Language: English
Status: Completed
Published: 2017-04-24
Updated: 2017-04-24
Packaged: 2018-10-23 09:32:25
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 1
Words: 9,988
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10716756
Author URL: https://archiveofourown.org/users/Rainbow_Sprinkles/pseuds/Rainbow_Sprinkles
Summary: There was one thing those humans had in common. They’d all been humans, yeah, but they were also all people. They’d had a mind, a will, and a constant of magic was that it required a will. Intent. Emotion.His father needed a person.Remembering is not a choice. To Sans, it's a responsibility.





	Wake yourself up; sleep yourself down

**Author's Note:**

> I usually avoid one-shots, but this insisted on being a one-shot. This is basically a headcanony Sans backstory. Focus is on familial relationships. Rated mostly for repeated instances of swearing and the generally unpleasant experience of being in Sans’s head.
> 
> As with all my works, I am my own editor, so kindly direct my attention to errors so I can fix them.

He wakes up. Fully alert immediately. That’s weird. He never _wakes up_ when he wakes up.

Drags himself out of bed. There is this strange confusion in his skull, and close on its heels is dread. He doesn’t know why. What does he have to dread?

Goes to his window. Snow. Lots of it. White as bone.

Why was he expecting no snow? Green, like the grass in the king’s garden. More light. He’s never woken up to that before. Why would he expect something he hasn’t seen?

Why does he want to go outside?

He does. Snowdin. It’s – he checks his phone – evening. Post-dinner. Papyrus should be in his room, either on his computer or playing out battle scenarios.

It’s always Snowdin. Why is he beginning to panic at the sight of his hometown?

It’s just his bullshit again, isn’t it. He shouldn’t worry about it. Panic takes energy. He doesn’t have energy.

Sans sighs and goes back inside. He’ll go back to sleep. That’ll help him avoid thinking about this.

 

* * *

 

Staying out of the way was always the best bet. Sans got into it with Gaster a few times when he was younger. When he thought the things he did made a difference.

He didn’t care at first. He could take care of Papyrus just fine. He liked being with his brother.

But then Papyrus got old enough to notice their father’s absence and it was _Sans, why does Dad work so much_ and _Sans, does Dad not want to see us? Is that why he’s never home?_ and when Sans stayed up late so he could actually talk to his father there was the guilt and the _I’m sorry I’ll try harder_ but their plans were constantly shoved aside for the sake of more work.

He’d heard, more than once, that he should be proud because his father was the Royal Scientist. Pride had nothing on the crushed expression Papyrus would wear when Sans told him their dad wouldn’t be joining them after all. Pride had nothing on the way his shoulders slumped, the anxious disappointment.

Sans made excuses and lied to Papyrus and tried to make everything okay. He encouraged him to try new things, helped him with his homework even as he slacked off on his own, complimented his ideas, anything he could do to build him up. Gradually his little brother became less anxious. He was eager to please, as ever, but he directed that eagerness towards other people, like his teachers.

Their father still apologized when he had no time for them. He didn’t have enough time to scold Sans for his lackluster performance in school. Sometimes he didn’t have enough time to eat. Or sleep.

Adolescence made Sans irritable and tired of the same shit. He marched into his father’s Hotland lab and demanded to know what the fuck he was working on and why it was more important than Papyrus.

Or… well, he was going to. He had a whole speech planned out and everything. Instead he marched into the lab only to see his father and a few technicians gathered around something he was too short to see.

He approached them. The technicians behaved normally, talking to one another and looking at whatever it was that was so interesting. One glanced up at Gaster and asked, “So what does this mean, Doctor?”

Sans stepped up next to his father, uneasy. He had never seen Gaster so still. The shocked look on his father’s face stopped him in his tracks, evaporated any anger he might have brought here with him.

He followed Gaster’s gaze. There was a small monitor mounted on a machine. There was a graph, it looked like, onscreen. Straight line starting at the left, continuing uninterrupted, only to branch into two three-quarters of the way across the screen. The upper branch divided again, and again, until there were almost a dozen endpoints. It looked like a little tree.

The lower branch continued on before branching once more. Again, the upper branch fanned out into a small tree, while the lower kept going. The lower line of the graph branched a total of eight times. One of the branches was just that, a single branch and nothing else, but others flowered upward, breaking off again and again into multiple paths. The two farthest to the right were huge, like feathery bouquets.

“Doctor?” the technician asked again.

Gaster snapped himself out of it. “This is not… the data I was expecting,” he says. “It needs to be rechecked. Shut it down and print out the measurements. I need to check my calculations. Make sure everything is in order. Recalibrate if necessary.”

Without so much as acknowledging at Sans, Gaster strode back to his office. The technicians exchanged a glance. Sans watched his father go. Looked from his office door to the monitor.

He didn’t understand.

 

* * *

 

She doesn’t make him do anything. She asks him. She asks for a promise.

 _Old lady, you don’t want me promisin’ anything,_ he thinks, but what comes out of his mouth is, “Sure thing,” because exchanging shitty knock-knock jokes is the only reason he gets out of bed some days.

She still doesn’t laugh as much. He wonders when this human will come out. There has to be one in there, or she wouldn’t be asking him to protect one. How’s he gonna protect a kid when his brother wants—

Wait.

Sans knows as much about humans as the next monster. Probably a little more. Their stuff’s always falling down into the dump. Makes it easy to teach young monsters what humans look and act like.

Humans come in different ages. How does Sans know the human somewhere behind this door is a kid?

 

* * *

 

It wasn’t genuine interest, at first. He thought if he got closer to his dad he could manipulate him into paying more attention to Papyrus.

Gaster dumped six textbooks into a shocked Sans’s lap, said, “When you’re done with those, I have more,” and promptly left him alone again.

Stubbornness was his first motivation. Then he started reading and became hooked. Human science. Magical theory. Within the last century, monsters had begun researching connections between the two. It had been due to their work Gaster had been able to find an application of their theory in building the Core, which had been regarded as an act of genius in and of itself. There was even a thin book with writings by human mages that Sans heavily suspected his father had taken from the castle’s library. The king probably let him, since they were friends.

Sans stopped going to school and started asking his dad questions. To his surprise, Gaster actually answered him. He had the technicians teach him how to use certain machines. He invited Sans to look over calculations and organize data.

At first he was clueless, and it was hard, but he got used to it. He learned how to read columns of data with a glance. He learned how to calibrate machinery. He understood the majority of his father’s calculations, and with that, he understood that his father was studying the passage of time.

Sans looked at the graph again, that branching tree with thousands of endpoints. Maybe hundreds of thousands. “I don’t get it,” he said. “Shouldn’t it be a single straight line?”

“We understand time to be linear,” Gaster replied. “We have obtained this data repeatedly. It measures the same way, every time.”

“So time’s nonlinear? Magic can’t manipulate time.”

“Monster magic cannot manipulate time.”

He took this in. “So… human magic. Humans are doing this.”

“Do you have a guess as to where we are?” Gaster asked.

Sans thought about it. Asgore had six souls. He knew the time between humans was increasing, and had been since they started falling. Maybe the fact that nobody had ever returned was a deterrent. Seven humans had fallen and only the first had ever made it back to the surface, but they’d made it back as a corpse, so. Moot point.

“We’re here, right?” Sans said, pointing between the last two branch points, between the two most voluminous trees on the graph. The two had almost no distance between them. They were almost on top of one another.

“I am unsure,” Gaster replied. “At first, I had your thought: seven humans have fallen, so we must be between the seventh and eighth anomalies. But consider _why_ a human would manipulate time. Humans have forgotten about us. They regard magic as supernatural and unreal, save for many and sometimes conflicting superstitious beliefs, which I will not consider because those beliefs have absolutely no evidence to back them up. So why would a human who believes they cannot do magic do magic?”

Sans frowned. “They didn’t do it on purpose?”

His father nodded. “Exactly. Now consider what the humans faced when they came here.”

“We were trying to get their souls.” It clicked. “We were trying to kill them. You think they accidentally turned back time when they died?”

Another nod. “Magic reacts to will and emotion – and anyone would experience intense emotion as they are being killed.”

There was a pause. “But why a tree?” Sans asked. “Why a branching graph? Why not… loops, or something?”

“This is only a two-dimensional representation. If we were able to get a three-dimensional representation, it would undoubtedly be more complex.”

He tried to imagine it. Turn the graph to the side, each endpoint continuing backwards, curling down and eventually connecting back to an earlier point.

“Here is the inconsistency,” Gaster said. “Nobody tried to kill the first fallen human. They became sick and died. It is easy to say the others panicked after being killed and accidentally rewound time, but the first human died under different circumstances.”

“Maybe they tried again but they kept gettin’ sick anyway,” Sans suggested.

“That is possible, but if that were the case, I would like to think they would have kept trying until their death did not cause so much collateral damage. The way they died was a major factor in the prince’s death, which then played a large role in the queen’s departure.”

“Yeah, but what if that _was_ the option with the least collateral damage?”

“Perhaps. Another possibility is that the first human never rewound time. Perhaps their illness made their death feel natural, so they did not resist it. Where would we be if this were the case?”

Sans hesitated, then pointed between the sixth and seventh branch points.

Gaster nodded. “This theory has problems, too.”

“Uh, yeah,” Sans said. “The king’s already got six souls, but if we’re here, we’ve got two more humans to go. We need one, not two. Why would we stay down here after we get the seventh soul?”

“Perhaps we will not acquire the soul of the seventh human. Perhaps it will shatter before we can capture it.”

There was another option. “Would anything other than a human be capable of doing this?”

“Not that I know of.”

“Can we stop them?”

His father’s face lit up. “That is what I am beginning to work on. Will you help me?”

Sans glanced at the graph again. If they could somehow take this power from the humans, getting the last soul wouldn’t be a problem. They could break the barrier, go to the surface… Papyrus had always wanted to see the surface.

He nodded. “Sure thing, Dad. Let’s get to work.”

 

* * *

 

They’re small, with a mop of brown hair and brown skin. Their clothes look scruffy. They’re skinny. The skin on their hands is uneven, there are some darker splotches and they have a scrape on one palm.

They can’t be very old. They’re shorter than Sans is.

They don’t have LV. They don’t have EXP.

That doesn’t stop him from reflexively wanting to shove a bone through their back. He could do it. They might die before they realize what happened or who did it. And what’s one human kid against the imprisonment of the entirety of monsterkind? He could end it. He could take the soul to Asgore. He could…

He could break his promise, but he won’t.

He smashes the branch once they pass it, just to see their reaction. They whip around, startled, maybe a bit frightened. When they begin moving again, they walk a little faster than they were before.

Their branch is a tree, with just as many endpoints as the one before it. Maybe even more. Sans knows his head is fucked, but it’s been… a few weeks? Maybe a few months?

He doesn’t even know. He’s like the vast majority of the residents of the Underground in that he doesn’t like to look at calendars very much. A lot of monsters aren’t even sure of exactly how old they are.

They literally just moved out of the seventh tree. He doesn’t know who it belonged to or when it started, though he wonders if he figured it out and then had his memories ripped from him when they turned time back.

A thought, sudden, unbidden: did this human _override_ the control of the owner of the seventh tree? Is that what happened? Theirs were the only two trees practically on top of each other, so…

“Human.”

They have frozen. They didn’t move during his approach.

“Don’t you know how to greet a new pal? Turn around and shake my hand.”

He did not almost say _old pal_ instead of _new pal_. He did not. He totally did not.

They turn. Sans is left-handed, so he reaches out with his left hand. They give him theirs, eyes wide.

They stare, startled, when the sloppy fart noise erupts from their conjoined hands. Then the outer corners of their eyes crinkle and their lips curl into a smile and they let out a quiet giggle.

It’s barely anything, but Sans feel the tension slowly drain out of him at the sight. Maybe… maybe they’ll be okay.

 

* * *

 

Gaster frowned at him. “Where are you going?”

Sans shrugged his jacket back on. During work, his father made him wear a lab coat, and actual _shoes_. It sucked. “Gotta go get Papyrus. He’ll be done with school soon.”

“We are almost done coding this, Sans.”

“I’ve been leaving at this time for weeks. Or did you not notice?”

His father understood the pointed jab, if the flash of annoyance across his face was anything to go by. “He is old enough to walk home by himself. He knows the way.”

“That has nothin’ to do with it. I like walking him home. He likes tellin’ me about his day. He likes the company, Gaster.”

People were watching. Sans had let his father know he didn’t spend enough time with Papyrus many, many times, but this was the first time he’d been so short about it. But he was gonna be late, and he was tired, and he probably wouldn’t have been short at all if his father had nodded and turned back to his work when Sans said where he was going.

“We can test out the new visualization system when we are done coding,” Gaster said. “I thought you understood how important this is, Sans.”

Sans stuffed his hands into his pockets. Looked at his father. “I do. But Papyrus is more important. One of us has gotta remember that.”

He left without another word.

 

* * *

 

He could ask them why, but he doubts he’ll get an answer.

He could ask himself why, but… heh. He isn’t even sure.

He’s killed them six times, by his count. They have already refused to spare him, but he got them with that once before. He must have. He hopes so.

Sans knows he should just quit. They’re going to come back again and again and again until they get lucky and kill him. They seem to remember his bullet patterns, which makes him wonder how far their memory can reach. Do they remember more easily if they only go back a little? Is going back a lot harder on them? Do they remember everything until a particular action and then nothing after that, or is it more of a spectrum?

Does their head feel as fuzzy as his does when they try to remember?

Isn’t it _worse_ if they remember? Doesn’t that mean they’re _choosing_ to kill people whom they know can be befriended? Whom they have befriended?

And, a thought that hooks into his head and doesn’t let go: what the fuck _happened_ to this kid that they would do something like this?

 

* * *

 

For a while Sans was put to training the new interns. He was still aware of overarching projects, but didn’t bother with them. He barely interacted with his father, but that was fine.

He started most of them off on spreadsheets. One of them – a monster named Alphys – he put on machines right away because she had a good mechanical instinct. She’d never seen this stuff before, but she caught on faster than most of the technicians had.

The interns didn’t free up time for Gaster. Instead he seemed to work more. Papyrus stopped mentioning him so often, instead opting to bring ideas for puzzles and new things he’d learned in school to Sans.

“No no no!” Papyrus cried out, snatching the notebook away from Sans. “I couldn’t possibly do that!! Creating an unsolvable puzzle – that’s cheating!!”

Sans leaned an elbow on the table and rested his jaw on a hand. “It’d be the easiest way to capture a human, bro.”

“I will capture a human!! But I have to do it right, or it won’t count!! _Then_ all the kids in school will want to be my friend!”

Sans felt his grin drop a notch. Papyrus was loud and overeager, he knew that, but his classmates didn’t know what they were missing out on. Papyrus was the best, and he deserved to know it. “You’re gonna be the best puzzle-creator ever, bro.”

Papyrus shot up out of his chair, fist extending towards the ceiling. “NYEH HEH HEH!!! I WILL BE THE BEST!!!” He paused, peering at Sans. “You really think so?”

Sans nodded. “‘Course. You’re the best bro ever. That’s already one thing you’re best at, so I know you can be the best at a lot more.”

“You are right!! How could I doubt myself!?!?”

“Yeah. You’re great, bro.”

“I am very great!! Oh!!” He stopped posing and leaned forward suddenly. “Sans, do you think if I capture a human, Dad will stay home more often!?!?”

Sans’s grin was threatening to fall off his face. Here he was, big brother parenting his little brother who was already taller than him and frankly not that much younger. He was inadequate. Gaster could have done a much better job, if he were ever _here_.

Sans was here. He’d have to do. “Of course, Paps. He’d be real proud of ya, I know it.”

His brother deserved more, but at least he was here.

 

* * *

 

Kid likes hot dogs, judging by how many they’ve got on their head.

It’s fine. Sans doesn’t bother looking at their LV or EXP. No point. No point in trying to stop them from killing. If they want to, they will, if they don’t want to, they won’t. Nothing he does changes it, so it’s better not to do anything at all.

He wonders how many times he’s had these thoughts before. How many times they’ve gone back. They have probably done this before, but if they’ve done _this_ before, why was he filled with such dread when they came out of the Ruins?

“Here’s another hot dog. It’s on the house. Well, no. It’s on you.”

They giggle. It breaks their typically neutral façade. They… only seem to do that when they’re stressed out. When they’re relaxed, he has seen them smile and wave and sometimes chat with people. Hell, they’ve even done some flirting here and there, even though they must be too young to mean it.

But sometimes… when they think nobody’s around, they gesture and produce facial expressions like they are talking to someone else. Sometimes they giggle. Sometimes they look mad. Sometimes they look like they’re about to cry.

Who are they talking to?

 

* * *

 

He had to be able to do _something_.

Gaster had been frosty with him for a while, but it didn’t take long for him to become totally absorbed in his work and forget about it. He knew he’d waste more time arguing with Sans than he would letting Sans do what he wanted, so he didn’t try to argue.

It didn’t take Sans long to find a bargaining chip. His father had been trying remotely to access the time magic using the multitude of machines in his Core lab. If the fallen humans had access to it, it stood to reason that it was simply available for their use. All they needed was to see a tiny anomaly between either the sixth and seventh trees or the seventh and eighth trees, but all efforts so far had yielded no results.

There was one thing those humans had in common. They’d all been humans, yeah, but they were also all _people_. They’d had a mind, a will, and a constant of magic was that it required a will. Intent. Emotion.

His father needed a person.

“No,” Gaster said as soon as Sans brought it up. “It is too risky. We need to acquire more information first.”

“You’ve gathered all the info you’re gonna get,” Sans replied. “You hit a wall. We’re not gonna learn anything else unless we try this.”

His father opened his mouth to argue and Sans cut him off. “You’ve been considering this for a while. I read your notes. Your biggest ethical concern was that a volunteer probably wouldn’t be able to grasp what you’re trying to do. They wouldn’t be informed. Are you gonna tell me I’m not informed? The only one who knows more about the theory than me is you.”

“You are informed,” Gaster snapped out. “You are also not of age, and most importantly, you are my _son_. I would be unable to remain objective if I used you as a subject. The experiment’s integrity would be compromised before we could even begin.”

“Funny you’re playing the dad card when you haven’t spoken more than two sentences to Papyrus in _months_ ,” Sans snarled. “You don’t get to do that. You don’t only get to be Dad when it’s convenient for you.”

“Would you rather I risk my children’s lives at every turn!?” It had been a long, long time since Sans had seen his father angry. He stood up, marched over to the tree-graph, which was tacked to a wall in his office, and ripped it down.

There was another graph underneath it. “Look,” Gaster demanded, sweeping a hand towards it. “Look and tell me what you see.”

Sans moved after hesitating. What was this?

Oh. He knew what this was. It was the no-longer-theoretical three-dimensional representation his father had mentioned when Sans joined his team a few years ago. The most telling image was the tree-graph turned on its side. Altogether, it was too much: loop upon loop upon loop, stacked on top of each other so thickly it was hard to tell them apart.

The other images were the trees separated from one another, sliced at the base and turned onto their sides. It was much easier to see when they weren’t layered on top of one another. The single-branch tree formed a single small loop. The others formed smaller loops inside bigger loops, and sometimes a single line would curl back on itself multiple times as it continued on. Some loops were made entirely of small circles, others didn’t have any intra-loop loops.

The seventh and eighth trees were still the biggest and most complex, but it was the eighth that caught Sans’s attention.

It was the only one with endpoints. Sometimes a line wouldn’t turn and find itself again. Sometimes they just stopped. Ended. Loose ends dangling. There weren’t many endpoints relative to the loops, but there were enough.

There really only needed to be one for it to be a problem.

“So you see,” Gaster said quietly, his anger gone. “There is a possibility that the eighth anomaly could end all of time. I cannot sit by and allow this to happen. It would obviously have a catastrophic impact on everyone, but my primary concern is for you and Papyrus. Neither of you were in danger before. Now I know you are.”

Sans stood there. He hadn’t meant to – he didn’t know what to do. He’d never seen his father despair like this.

“Dad.” His voice sounded wrong in the oppressive quiet of the room. “I – understand. I still want you to use me.”

Gaster’s gaze snapped down to him. Sans raised both hands, palms-out. “I understand the risks. I understand what I’m asking you to do. With this on the table… you should let me. But I’m still asking.”

 

* * *

 

He stares down at Papyrus’s dust. He expected this from the way they went through the forest, from the way they wouldn’t let Papyrus explain his puzzles, from the way they stared blankly at him when he got them with the prank handshake.

He didn’t bother. He can’t even make himself hate himself for it. He doesn’t feel much of anything at all.

He knows himself too well. Better not to do anything, because by taking action he would undoubtedly fuck something up. And then Papyrus…

Heh. Papyrus is dead. Sans is willing to bet the old lady behind the door is dead, too. And if the human is moving as quickly as they did through the forest, they’re probably already through Hotland, maybe even the Core.

He has nothing to lose. Why not try to do something, for once?

 

* * *

 

The Hotland lab was primarily for theorizing, the Core lab was for experimenting. The Core lab was the only accessible room in the lower hemisphere of the Core. Everything else served the function of energy conversion, storage, and distribution. The pod Sans was lying in was suspended over a pit. It was surrounded on three sides by generators, which were several stories tall and extended down into the seemingly never-ending abyss below.

Gaster’s voice came over the speaker next to his head: “I am going to attempt to connect you now. The number is eight-hundred-fifty-two-thousand-six-hundred-ninety-three. Do you have it memorized?”

Sans repeated it a few times in his head. “Yeah.”

“If you succeed, move time to before you entered the pod. Tell me that number.”

“We need a better codeword. Somethin’ funny. Like I’m a stupid doodoo butt.”

“That is incredibly immature,” Gaster replied, though Sans could tell he was trying not to laugh. “I need to know you’re taking this seriously, Sans.”

“Just tryin’ to lighten the mood, Dad.”

“Right.” His father sighed. “Are you ready?”

He was shaking. He clenched his hand over the emergency kill switch. “As ready as I’m gonna be.”

“Alright. Hit the kill switch the _instant_ you feel you need to, understand? This can be replicated. You cannot be replaced. We are attempting to connect… now.”

Sans felt something _move_. Something that wasn’t supposed to move. It was nowhere and everywhere, it was _located_ nowhere and everywhere, but it also was all the nowheres and everywheres and he got the sense of vastness, emptiness, lack of direction, points of absoluteness, everything that was and who was he, in this indescribable everything?

There was a thought, sudden, of _I am being watched, we all are,_ before it began to feel like he was being ripped in half and he passed out.

 

* * *

 

He wakes up. His room in Snowdin.

Just the _thought_ of getting out of bed takes more energy than he currently possesses.

He rolls over and goes back to sleep.

 

* * *

 

He woke up to Papyrus’s tear-stained face. “SANS!!!” he wailed. “YOU’RE AWAKE!!!”

“Heya Paps,” Sans forced out, and just talking made him want to go right back to sleep.

“Be careful, Papyrus,” Gaster said. Sans glanced to his other side, surprised to see him there. He looked absolutely haggard.

Papyrus sniffled and very gently hugged his older brother. Sans tried to raise his arms to return the favor, but he was too tired to lift them.

Gaster placed his hand on Sans’s other shoulder. “Don’t strain yourself.”

“What happened?” It came out a little slurred. He was fighting to stay awake. He was at their home in New Home. Someone had put fresh sheets and blankets on Sans’s bed before sticking him in it.

His father hesitated. There was movement in the doorway – what the fuck was the king doing here?

Gaster turned to him. “Asgore,” he said softly. “Could you do me a favor and take Papyrus into the other room?”

“No!!” Papyrus cried. “I want to stay with Sans!!”

“You will,” Gaster assured him. “First Sans needs to rest. It’s very important to his recovery.”

“I can b-be quiet,” Papyrus was sobbing, not quietly at all. It broke Sans’s metaphorical heart.

“Not right now, Papyrus,” Gaster said. His tone was final, but soft. “Why don’t you help Asgore make some tea? I am sure Sans would like a drink when he wakes up. Be good for the king.”

Asgore held out his hands. “There, there, little one. Come here. It is alright.”

“Okay,” Papyrus hiccupped. He took one of the king’s big hands.

The king rose to his full height and glanced at Sans. “It’s good to see you awake,” he said. “I hope you feel better.” Papyrus clung to his hand as he led the young skeleton out of the room.

Gaster followed them far enough to shut the door. He came back to Sans’s bedside. Sans couldn’t even begin to process the expression on his face. “You almost died,” he said. “You became unresponsive. I threw the external switch and pulled you out—”

He was so tired, but he forced himself to talk. “What did we get?”

“You are not to concern yourself with that.” It came out sharp, but Gaster’s shoulders quickly sagged. “I’m not exactly sure, yet,” he murmured. “Making sure you were okay came first.”

“I’m tired.”

“You should be. You have been asleep for days. We tried healing magic on you, Sans. Your soul is stable, but… your stats suffered a blow they have yet to recover from. They may not recover.”

He went to concentrate, to try to check himself, but his father shook his head. “Don’t. You will exhaust yourself again. Your HP is _ten_ , Sans. Your ATK and DEF are even lower.”

There was so much left unsaid. Like how having a bad day could make him ill. How even a friendly sparring match could severely injure him. How _babies_ usually outgrew a single-digit HP in their first year.

“The world’s so much bigger than we thought,” Sans said. “Don’t you want to know what happened on my end?”

“When you have recovered, yes,” Gaster replied firmly. “Until then, you are to focus on getting better. You will not know what is happening at the lab. You do not need to stress yourself over it. Is that clear?”

It wasn’t like he had the energy to argue. It took all his strength to keep his eyesockets open.

His father’s demeanor softened. He reached out a hand and stroked it along Sans’s skull. “Get well.”

His eyesockets closed. “Worth it,” he muttered. He was a poor substitute for their father to Papyrus. He was unable to reason or work on his father’s level. At least he’d been useful in this way.

“It wasn’t,” Gaster said, and Sans fell asleep.

 

* * *

 

“SANS!!”

Too early, Papyrus. Way too early.

He opens Sans’s door. Sans pulls the sheet over his head. “Sans, wake up!” Papyrus demands. “We have to get to our posts!”

He doesn’t move. Papyrus approaches. “Sans? Are you alright?”

There’s an underlying uncertainty in his tone that Sans was hearing more of lately. Papyrus used to just assume he was fine. Now he has to put forth an effort to convince his brother of his okayness.

“Paps,” Sans utters.

“What?” Papyrus is beginning to sound both confused and worried.

“Why didn’t the skeleton go to the dance?”

Two seconds’ pause, then Papyrus says, tone irritated, “Sans.”

“Because he had no body to go with.”

“That was mediocre at best.”

“The bad ones are the best, bro. Hold on, I got another one. Why are skeletons so calm?”

Papyrus sighs, but says, “I don’t know, Sans. Why are skeletons so calm?”

“Because nothing gets under their skin.”

Sans giggles. Papyrus pulls the sheet off Sans’s head. “I know you have a tendon-cy to tell awful jokes, but I hope that’s all you have for today.”

“Aw, you’re tickling my funny bone.”

“My joke was of high quality!! Cease your boondoggling at once!! We must get to our posts and be on the lookout for a human!! And—” he pauses to pose, grinning brilliantly, “I have a very good feeling about today! Today will be the day, I know it!!”

He bounds excitedly out of Sans’s room. It’s actually pretty easy to find the energy to roll over and stand up. Papyrus tends to have that effect on people.

But… Sans has a feeling about today, too. And it’s not a good feeling.

 

* * *

 

He was in bed for days and at home for weeks. He slept and slept and slept and slept.

The first few days, Gaster was home all the time. He took care of Papyrus and Sans with an ease of which Sans was simultaneously jealous and appreciative.

The king visited again, once, but more often the lab technicians or interns would come by. They wanted to know how Sans was doing. He hadn’t expected any of these people to ask after him. He didn’t know why he didn’t expect it, but he didn’t. Alphys stayed with him for almost eight hours once so they could watch a human cartoon she’d brought with her.

He got better. He was still tired constantly, but he was able to get up and move around and use magic without a problem.

Gaster went back to work. Papyrus, who had done a lot of caretaking while their father tried to work from home, kept hovering over Sans despite assurances that he was fine.

Stats and fatigue aside, he _was_ fine. There was… something different. Like he had a sixth sense. Like there was something _there_ that nobody was acknowledging.

He was too scared to touch it again. He went to the lab only for Gaster to promptly take him back home. Sans promised to stick to watching the interns and doing calculations. He knew Gaster would never let him be the subject of an experiment, but he wouldn’t even let Sans be useful in stupid, mundane ways.

But he did tell Sans when he was ready to try again.

“This increased awareness of something you cannot describe likely means we were at least fractionally successful,” Gaster said. He shrugged out of his lab coat. “We have made adjustments to the machines and procedure.”

“But using _yourself_?” Sans said. “That’s a bad idea. You need to be out here.”

“I am the logical choice,” Gaster replied. “You and I are the only people I would consider to be completely informed. My stats are higher than yours were. If the cost is a reduction in stats, I have more to give up than you did.”

What Sans heard was _you were too weak for this and that’s why it failed_. He shook his head. Gaster never said that, even though it was probably true. “This could kill you.”

“It did not kill you.”

“You were there to stop it and get me out.”

Gaster turned to him, stooped, and put his hands on Sans’s shoulders. “Yes, and that is why I invited you here today. I want your hand on the kill switch should I fall unconscious, as you did.”

There was a pause. Sans knew he still looked uncertain. “Sans, you are the only person I want to trust with this,” his father said quietly. “I won’t make you. I am asking.”

He kind of wanted to hit him, because it was the same manipulative bullshit Sans had pulled to get his dad to let him in that pod. Just as it had worked then, it was working now.

He shrugged Gaster’s hands off his shoulders. “Fine. Let’s do this.”

The technicians were excited, but the interns weren’t here today. The set-up looked pretty much the same, except for a brand-new machine that was only connected to the pod and not to any of the other equipment in the room. It didn’t even look like it was connected to a power source.

“What’s that?” Sans asked.

Gaster guided him over to the machine. “This is your station. We moved the external kill switch over here. Should I access time-manipulating magic, this will serve as a storage device.”

What? Store that… whatever that Sans knew encompassed all of them and so much more than they were even aware of? “Not sure it works like that, Dad.”

“That is precisely what we are trying to figure out. This is another safety measure.” He handed Sans a headset identical to what the technicians were wearing. “I will communicate with all of you through this. You are only to throw the kill switch should I fall unconscious, understand?”

Sans didn’t want this responsibility, but if not him, who else? It was the same question he’d asked himself over and over while his father was at work and Papyrus was lonely at home.

He put the headset on. “Yeah, I suppose.”

Gaster got in the pod. Sans stood at his station. The technicians waited for his go-ahead. “Dad, can ya hear me?” he asked.

Gaster’s voice came through the headset, smooth and calm. “I hear you, Sans.”

“Good. Codeword’s I’m the legendary fartmaster.”

His father chuckled. “Sans.”

“That’s your codeword.”

A few of the techs coughed to hide their amusement. Gaster snickered again. “Fine. I am ready, son.”

Sans waited. “System check complete,” one of the techs called. “No warnings.”

“Proceed with the connection,” Gaster said.

The Core’s constant humming grew louder. “Sans,” Gaster said almost immediately. “This is… difficult to describe. There is something _more_ , something that stretches beyond our world and… envelopes others.”

“You okay?” Sans asked immediately.

“Fine, I’m fine. Other… I do not know if worlds is the correct term. But perhaps instead of winding _back_ time, the human anomalies created another path for time.”

“That doesn’t make sense. You found a significant increase in feelings of déjà vu during the time of the last human. If you’re talkin’ parallel universes the déjà vu wouldn’t happen.”

“You are right, but perhaps it is not that absolute. I understand now why you had difficulty describing it.”

One of the machines began to beep. Loudly.

“One of the generators in the Core failed,” the tech called. “It should be fine, as long as—”

Right on cue, the beeping increased in frequency and volume until it was a full-blown alarm.

“We’re losing generators,” another tech said, typing furiously at their keyboard. “Or… not? It’s showing an error, but these readings are atypical for a loss of power—”

“It could go the other way,” someone else added. “If they’re overloaded with magic or power or… _something_ , we wouldn’t be able to tell. Our system isn’t designed to _read_ overload because there’s nowhere we could even get that much power—”

“Time to quit, Dad,” Sans said. “The Core can’t support us while we do this.”

“It can,” Gaster replied. “Leave the current generators alone and reroute to those powering New Home. Asgore will understand the necessity.”

“But—”

“How are my stats?”

“Holding steady,” someone replied.

“Then we continue.”

Sans’s fingers twitched on the kill switch. How pissed would Gaster be if he threw the switch? Maybe he wouldn’t let Sans in the lab the next time he was ready to try this again. His father said _only_ if he fell unconscious, right? Sans wasn’t sure he wanted to wait that long.

The alarms shut up as the techs worked. Gaster had begun muttering to himself. Sans only caught bits and pieces, like, “So vast – getting darker – others that are – how to establish—”

“Gaster _,_ ” Sans said. “How are you doing?”

“Wonderfully,” Gaster responded promptly. “This will provide us with so many more opportunities for experimentation. We—”

“Okay, great, but where are you at on the time manipulation? You got anything?”

“I… no, I don’t. The experience you described, I am feeling it too, but it is still linear. It…” he paused. “It feels like it has more characteristics of space, not time, but allow me to attempt to make some objective observations. I apologize; I was caught up in the enormity of this.”

There was one second of silence, two – then the alarms started up again. “Dad,” Sans said.

“Reroute—”

“It isn’t the generators failing this time, it’s the whole _Core_. It’s on the verge of shutting down.”

“Dad,” Sans said again. He didn’t need to hear more than that from the technicians. “We gotta stop.”

“Absolutely not,” Gaster replied irritably. “We are on the precipice of—”

“Sans, you _have_ to get him out,” one of the techs said. They were shouting at one another over the alarms, trying to get the situation under control.

“Gimme a minute,” Sans replied. He was sweating. “Dad, we have the option to try again later. This isn’t more important than the Core.”

“You did not observe this, you only caught a glimpse of it—”

“It doesn’t _matter_ ,” Sans interrupted. He was on the verge of yelling. “It’s not more important than the Core, it’s not more important than _you_ , and I fuckin’ hope you think it’s not more important than me and Papyrus. We’re done.”

He threw the kill switch.

Nothing happened.

“Sans, when I decided I would be here and you would be out there, I exchanged the authority of the kill switches,” Gaster said. “Yours only works if I fall unconscious and my hand comes off mine.”

The room rumbled. One of the machines started to smoke. The techs were yelling, alternating between ignoring Sans and shouting at him to throw the switch. That all faded into background noise. Sans felt like he was nestled in his head. He was watching things happen through his eyesockets. He wasn’t participating. It wasn’t real.

“Our entire world…” Gaster said. His voice was soft, smooth, and had a rare trace of awe within it. “There are others. We are almost certainly interacting with one, though I do not yet know how. If we can—”

A sudden, awful rending reverberated through the room, which shook so hard Sans and his station were thrown to one side. One of the converters on the opposite wall exploded, sending smoking shrapnel careening through the room. Yelling was replaced by screaming. As a skeleton, Sans was not particularly sensitive to temperature, but even he could tell it was getting warmer.

Before he could even decide to stand up, the Core shifted again – and the supports holding up the pod his father was in snapped. One second it was there, and the next it had dropped out of sight.

“Gaster,” Sans said into the headset, but even as he stupidly hoped for a reply he knew it was idiotic to expect the headsets to keep working while everything else was literally crumbling around them.

So… this was it, then? He was going to die lying on the floor, clutching onto the corner of a useless machine. Alright. At least that meant he wouldn’t have to bother processing what had just happened to his father.

No. Papyrus was at school. He was old enough to walk home by himself, but Sans would rather chew off his own leg than let Papyrus come home to nobody. Papyrus needed him. He couldn’t die here. He needed to be at home for Papyrus.

That stupid _thing_ was still there. That thing Sans had caught a glimpse of. That thing Gaster had killed himself and everyone else here over. That thing Sans was still, to this day, aware of.

Space, Gaster had said. Space, not time. Space, not time. Space, not—

The feeling was horrible, and for a moment Sans was convinced he actually was dying, this was it, which wasn’t fair, because with his newly-low HP dying should have been quick for him—

It was quiet. He writhed in pain for a few seconds, unaware it had disappeared, then paused. He was still horizontal on a floor. It was not the lab’s floor. Not the same floor.

Sans rolled on his back. Looked around. He was home.

He promptly passed out. At least he was already lying down.

 

* * *

 

“Do you get what I’m saying?” he asks. He wants to see them react. Make their face move. “That promise I made to her… you know what would have happened if she hadn’t said anything?”

Nothing. The human just watches, waiting.

“…Buddy.” Might as well give it to them, then. “…You’d be dead where you stand.”

And. Nothing. No expression. No reaction.

“Hey, lighten up, bucko! I’m just joking with you.” Can he bait them? “Besides… haven’t I done a great job protecting you so far? I mean, look at yourself. You haven’t died a single time.”

They stare disbelievingly at him. “Hey, what’s that look supposed to mean?” he asks. They’re still a kid. He’s an asshole adult. Of course he can bait them. “Am I wrong…?”

They immediately force their expression back into neutrality. Yeah. Not hiding it, kiddo. He should know, because he hides everything.

“Heh,” he says. He meanders away from the table. “Well, that’s all. Take care of yourself, kid. ‘Cause someone really cares about you.”

 

* * *

 

For a second he was confused. Then it all came flooding back and he shot to his feet.

Too fast. He almost fell over again.

The machine he’d been stationed at was with him, however he got here. Its cables were ripped, it’d been pelted with debris, and it was damaged from where it had come unbolted from the lab floor and fallen over, but it was here.

It wasn’t like he got here naked. However he’d moved here, objects he’d been in contact with at the time had been able to come with him.

Okay. He reached for it again, and again, he felt himself… passing through it, or something. He couldn’t tell whether he was pulling it or it was pulling him.

He landed in the middle of his room with the machine. Still dressed. He could bring inanimate objects with him when he… teleported. Because that was what it was, right? He couldn’t leave the machine in the middle of the living room for Papyrus to see—

Papyrus, who would be getting out of school any minute. Papyrus, who didn’t know.

Sans had to get to Papyrus.

When he was spat out on the road in front of the school, he fell over, right on time for the bell to ring. A few people glanced at him, but he quickly scrambled to his feet, fighting the urge to check out again.

The students poured out. “HELLO, SANS!!!” Papyrus greeted him as soon as he came into view.

“Hey, Paps,” Sans responded. He was sweating crazily, exhausted. Space, not time. He could teleport because it’d been space, not time.

Papyrus led the way home. He always slowed his pace for Sans, but Sans was lagging more than he usually did. Papyrus talked, and talked, how he always did. Sans tried his best to pay attention, but—

“Did you just say power outage?” Sans asked.

Papyrus nodded. “It lasted almost twenty minutes! We moved outside so we could continue to study!”

Sans’s head was ringing. He wondered how long he’d been passed out on the floor.

When they reached their street, Papyrus stopped abruptly. He looked confused. “Paps?” Sans asked.

“I…” Papyrus began. “I… forgot where I was going. Or why I was going this way. Nyeh heh heh, how silly of me. Sans, do you know?”

What the…? “Uh, yeah. Just follow me, Paps.”

Every step sent dread up his spine. It wasn’t sinking in. Their father was dead. His whole team was dead. Sans was going to have to tell Papyrus their dad was dead.

Papyrus still looked confused when they reached their little home. They went inside.

Sans didn’t notice, at first. Papyrus chattered at his typical pace. Sans checked UnderNet first, and there it was. All anyone was talking about. An accident at the Core. How it had killed people. The Core was fine – apparently it had stabilized after they’d stopped siphoning its power.

As Sans read through what everyone had to say, the king issued an official statement. They were working on figuring out who had died, they were going to check and recheck the safety measures surrounding the Core, anyone who knew somebody was missing was encouraged to report to the castle.

Was he going to be the coward who let Papyrus hear about this from someone else?

No, but he was going to stall. He checked on Papyrus, then went into Gaster’s room.

Gaster was not here often. He usually lived out of his labs. Most of his belongings had been at the Core lab, since that was where most of his work was of late. He did not keep many belongings in their house.

But there was _nothing_ here. It looked like an unused guest room, which was how Sans expected it to look, but why couldn’t he _remember_ his dad living out of this place? It all felt fuzzy and weird and _gone_.

He wandered back out into the underused kitchen. Papyrus was sitting at the table, already doing his homework, determined expression on his face. “Paps?” he asked, half-dazed.

Papyrus set his pencil down. “What is it, brother?”

“I… gotta tell you something.”

“Well, what is it? Don’t keep me waiting!!”

“I… it’s about Dad. Look, I know this is really sudden… and I’m really, really sorry, but…”

He trailed off when he noticed his brother’s confusion. “I’m sorry, Sans,” he said, and he truly sounded apologetic. “But I do not know who you are talking about?? We’ve… never had a dad.”

It was oppressive, he’d noticed. That thing. That thing he’d gone through in one place and came out somewhere else. That thing that had captivated Gaster and blinded him to its danger. That thing that had saved Sans’s life.

“I mean, I don’t remember having a dad!!” Papyrus added quickly. Sans supposed something was showing in his expression. “If you say we did, I’m sure we did!! But you are older than me, so perhaps you remember it and I do not? Before he… well, I suppose he would have fallen down.”

Sans abruptly realized that in all Papyrus’s chatter on the way home, he had never once mentioned Gaster, or even implied he had any awareness of their dad.

Was he going to tell Papyrus about Gaster only to tell him he was dead?

Sans plastered on a big, fake grin. “Of course, Paps. Don’t worry ‘bout it. I got confused. Do your homework.”

Papyrus beamed at him. Turned back to his assignments.

Yeah. Sans was a coward, but he knew that already.

 

* * *

 

LV 1. No EXP.

“You never gained LOVE, but you gained love,” he says. “Does that make sense?”

The kid grins, and nods.

 

* * *

 

The next day, Sans went to see the king. He knew it wouldn’t be too suspicious, even though Asgore was busy. They had identified all monsters who had died in the ‘accident’ _except_ Gaster. There was no mention of the Royal Scientist at all on UnderNet. Sans had gone back to the Hotland lab and it seemed like most of Gaster’s stuff had just… disappeared. Sans had stashed some copies of blueprints in the basement because he had copies at home, but he took his dad’s Royal Scientist ID badge. And the single family photo Gaster had kept in the Hotland lab.

The closest Sans had ever been to the king was… when? Oh, right, when he’d almost died in the same pod that became his father’s coffin. Asgore had been there, Asgore had briefly distracted Papyrus. Right?

Why were his memories becoming selective? What was wrong with his head?

As he headed for the Throne Room, Sans realized this was unsafe. Someone could ambush the king while he was watering his freaking garden. Someone needed to watch this hall.

Asgore was humming to himself. He was on his knees, plucking weeds up by the roots. It would be so _easy_ for a human – the seventh or eighth anomaly – to walk right up to him and stick a knife in his back.

Sans had stared for too long, because Asgore glanced up. “Oh, howdy! I didn’t see you there.” He pushed himself to his feet and even with the distance between them, Sans was reminded that he was quite short. “How may I help you?”

This wasn’t right. The king remembered everyone and he was nice. He should have asked Sans how he was. The last time they interacted, Sans had been bedridden.

“Hey,” Sans said. He was forcing it out. “Uh, sorry for botherin’ ya, Your Majesty… do you recognize me?”

The king’s expression was politely confused. “No, I do not, young one. I apologize. Have we met before?”

“Nah. I just… thought you might know my dad.”

“What is your father’s name?”

Asgore had been good friends with Gaster. When Sans had been very young and still in school, the king had visited Sans’s class to talk to them about responsibility. Afterwards, he’d told Sans that he was friends with Gaster and Sans had been in utter awe. Asgore had _only_ known who Sans was because he knew Gaster.

If he didn’t recognize Sans…

Sans grinned. “Whoops. I was thinking of someone else. Sorry for wasting your time.”

He turned to go, then stopped. “Oh, uh, King Asgore?”

“Just Asgore is fine, young one.” The king smiled patiently, tinged with concern. “Are you sure you are alright?”

“I’m fine. I was… thinking. The post for Royal Scientist is open, isn’t it? You should probably start lookin’ to hire somebody.”

Asgore blinked. That was that same confusion he’d seen on Papyrus’s face. “Royal Scientist,” he repeated.

“Yeah.” Sans nodded. “It’s open, right?”

“It is.” The king still looked confused. “I will… look into that. Thank you.”

 

* * *

 

He knows nothing. This has always been the case.

He should not do anything. Every time… he has fucked up, every time. No matter what he does.

Someone asks him to take a break from fighting. Are they fighting? It’s tempting. He does the least amount of damage by doing nothing, and taking a break is pretty much doing nothing, right?

“Just give up,” he says. “I did.”

He survived by a fluke. He should have died that day. He couldn’t understand it, couldn’t replicate it, fuck, he couldn’t even serve as a proper experimental subject. He has always been inadequate and that is not going to change.

“Why even try?”

Are they fighting? Does it matter? He cannot be relied upon, he knows that. That is why he does not make promises. Whatever he chooses is automatically wrong by virtue of being his decision. When he screws it up, he can’t fix it, either. He can’t fix it.

Someone – who? – tells a bad skeleton pun. He sort of wants to laugh at it, but…

“You’ll never see ‘em again.”

And a small, childish voice cuts through the haze around his soul: “I’ll think about what I’ve done. I promise.”

Sans blinks, and it’s like waking up, except it’s also like having a good dream, for once.

He nods solemnly. Papyrus is with him. The kid is with him. He is not alone, and even though he doesn’t exactly feel whole or right, he knows the human needs support. They’ve been a good friend. This time.

“Nah,” he says, “I’m rootin’ for ya, kid.”

 

* * *

 

It didn’t take long to figure it out. Nobody could remember Gaster, not even Papyrus. Sans’s own memories were getting increasingly unreliable and it terrified him. He kept looking at the few things of Gaster’s he had to remind himself.

He moved the machine to Gaster’s old room. He couldn’t keep it here forever. If he wanted to fix it and figure it out, he’d need solitude and space.

Regardless of that, he had to move himself and Papyrus. He couldn’t afford to live in New Home. Gaster was gone, his stuff was gone, their income was gone. Sans could sell the house to get some money. That would cushion them at least until Sans could find a place and get a job. He could pass himself off as an adult. He was close enough, anyway.

Snowdin and Waterfall both had schools, right? What would be better for Papyrus? Where was the rent cheapest? He would have to do some research.

Maybe… he could fix this and figure out a way to bring Gaster back. Maybe he could get it done before the next anomaly started messing with time. Maybe this feeling like his soul was being crushed would only be temporary because his father wasn’t _dead_ dead. Not technically. Not forever.

Those were pretty big maybes. And it was Sans, so the maybes were even bigger.

But he swore – Papyrus would always come first. He would not put this machine above his brother.

Gaster had made that mistake. Sans wasn’t his father. He was sure he would fuck up in a lot of ways – whenever he could, probably – and he’d fuck up things Gaster would never have gotten wrong. But Sans refused to make that particular mistake. He would always, _always_ prioritize Papyrus.

After all, Papyrus was all Sans had left.

 

* * *

 

There is waking up, Frisk waking up, hanging out after Frisk sprints out of the room, wild-eyed, figuring out the queen’s pretty cool (she likes bad jokes, of course she’s cool), and waiting around. Lots of waiting around.

That’s okay. Sans needs a moment anyway.

Not forgetting has its consequences. He is seeing it right now in how Asgore and Toriel are trying not to look at each other. He is proof it has its consequences, too. So is the machine in the basement he never managed to fix up properly.

Maybe he’ll forget soon, though. Maybe Frisk will go back, and… well. Even if he can’t remember, he knows.

Maybe not forgetting and remembering aren’t exactly the same thing. Maybe he can use this. Sans loved his father, yeah, but there was resentment, too. Maybe he can let go without forgetting.

Toriel and Asgore are clearly both holding onto the idea of the family they had so long ago. Sans can tell it’s not doing them any favors. Maybe these people could be his new family.

Maybe Frisk won’t go back.

That’s a big maybe.

The kid returns later. They seem sorta forlorn. Sans wonders where they went, but doesn’t ask.

Even Papyrus and Undyne are silent as they exit the Underground. Nobody has the capacity to speak yet. They are all too busy looking.

The light is bright and it touches everything. He can see in all directions. He can look up and see the sky.

Instead of gawking, he turns and catches Frisk’s gaze.

They stare at him for a few seconds. He doesn’t have to say anything. They nod and face forward once again.

Sans looks at the sun, the land, the sky. He could get used to waking up on the surface.


End file.
